Jennifer Garner is clearly not letting herself go in the wake of her split from Ben Affleck.

The 43-year-old mother-of-three looked slim -- and had a huge smile on her face -- when she was spotted working out with a trainer last Sunday near her home in Brentwood, California. Sporting a basic white tank top, workout pants and sneakers, Jen practically glowed while going makeup-free.

She also ditched the wedding ring.

WATCH: Jennifer Garner Is Back In Los Angeles -- No Ring, New Nanny?

The Dallas Buyers Club actress appears to be slowly but steadily adjusting to the single life, since announcing her split from Affleck in June after a decade of marriage. Last Friday, Garner was spotted back in the Pacific Palisades, California home that she shares with Affleck, after filming wrapped in Atlanta on her latest film, Miracles From Heaven. She was seen with a reported new nanny, after the former couple let go of 28-year-old Christine Ouzounian, who reportedly had an affair with the 42-year-old Batman v. Superman: Dawn of Justice actor.

Affleck's rep has strongly denied the allegations, calling the original report "complete garbage" and "full of lies" in July.

Despite all the nanny drama, Garner and Affleck are putting on a united front for their three children -- Seraphina, 9, Violet, 6, and Samuel, 3. Last month, the former couple spent the Oscar-winning actor's 43rd birthday together by having a low-key family weekend in Orlando, Florida.

WATCH: Ben Affleck Has Officially Ditched His Wedding Ring in L.A.

Watch the video below to see how Garner is moving on with her life, now that she's back in L.A.